What ratio/propeller for Yanmar 2YM15

[Kasper]

Hi,

I am looking into the project of replacing my old VP 2001 with a 2012 Yanmar 2YM15 with 450 hours on it.

Therefore I will need to buy a gearbox and a new propeller. The question is what gearbox ratio and propeller size I should go for. My boat is a 1972 Hallberg Rassy Mistress 32, fin keel weighing 3,5 mt. My current VP 2001 is paired with an MS2B-L 2,3:1 ratio.

The Kanzaki KM2P-1 gearbox comes in the following ratios:
2.21/3.06, 2.62/3.06 and 3.22/3.06.

I would appreciate som help with this, your general thoughts on the engine change and other useful information for a novice mechanic.

Thank you!

[bil56]

I would say that 15hp is not much for such a boat weight ...
the closest would be the 2.21 ratio.
it remains to choose the right propeller, what type did you have?

./.

[Adelie]

The Yanmar doesn’t have its own transmission?

[skipperpete]

Originally Posted by Kasper

Hi,



I am looking into the project of replacing my old VP 2001 with a 2012 Yanmar 2YM15 with 450 hours on it.



Therefore I will need to buy a gearbox and a new propeller. The question is what gearbox ratio and propeller size I should go for. My boat is a 1972 Hallberg Rassy Mistress 32, fin keel weighing 3,5 mt. My current VP 2001 is paired with an MS2B-L 2,3:1 ratio.



The Kanzaki KM2P-1 gearbox comes in the following ratios:

2.21/3.06, 2.62/3.06 and 3.22/3.06.



I would appreciate som help with this, your general thoughts on the engine change and other useful information for a novice mechanic.



Thank you!

From the Yanmar manual[ATTACH]268115[ATTACH]268116

[Kasper]

Originally Posted by bil56

I would say that 15hp is not much for such a boat weight ...
the closest would be the 2.21 ratio.
it remains to choose the right propeller, what type did you have?

./.

My previous 9hp 2001 (probably less due to age) would push the boat to 5 knots without issues. I have read that 4hp per ton should be sufficient, while some modern boats are built with 6hp per ton. The option above would be to go for a 18hp VP D1.20 or something similar, but I have found a great deal for the 14hp 2YM15 pushing me in that direction.

Thoughts?

[Adelie]

Originally Posted by Kasper

My previous 9hp 2001 (probably less due to age) would push the boat to 5 knots without issues. I have read that 4hp per ton should be sufficient, while some modern boats are built with 6hp per ton. The option above would be to go for a 18hp VP D1.20 or something similar, but I have found a great deal for the 14hp 2YM15 pushing me in that direction.

Thoughts?

I believe the old rule of thumb was 2hp/ton which would push most boats to hull speed in flat water and about 2kt against 20kt wind with 2nm fetch.

More recently it has been 4hp/ton which will push you to hull speed against some wind and waves. I think that 6hp/ton is more HP creep.

[Pete7]

Originally Posted by Kasper

My previous 9hp 2001 (probably less due to age) would push the boat to 5 knots without issues. I have read that 4hp per ton should be sufficient, while some modern boats are built with 6hp per ton. The option above would be to go for a 18hp VP D1.20 or something similar, but I have found a great deal for the 14hp 2YM15 pushing me in that direction.

Thoughts?

Where are you planning to sail? If it's just in the Baltic with no tides and just a slight clockwise current then perhaps. However, if you plan on venturing further in the future, 14hp is a bit short for pushing against tides.

Are both the Yanmar and the Volvo new? How about Beta 20 or Nanni 21 with a down angled gearbox?

Pete

[Kasper]

Originally Posted by Pete7

Where are you planning to sail? If it's just in the Baltic with no tides and just a slight clockwise current then perhaps. However, if you plan on venturing further in the future, 14hp is a bit short for pushing against tides.

Are both the Yanmar and the Volvo new? How about Beta 20 or Nanni 21 with a down angled gearbox?

Pete

Planning to sail in Skagerak and Kattegat.

I have found a good deal for a used Yanmar 2YM15 with 450 hours on it. Have agreed on 1500£, incl lots of extras like filter, cables, etc.

I have not found a reasonable Volvo or Beta for sale. New engines are above my budget sadly.

[bil56]

I repeat my question: what propeller type did you have with the Volvo 2001?